A durable, low-cost electrogoniometer for dynamic measurement of joint trajectories.

This article introduces a method and step-by-step instructions for the design of a low-cost, flexible electrogoniometer, suitable for kinesiology, rehabilitation, and biometric applications. Two unidirectional flexible sensors are placed back-to-back, and a multivariate linear regression model was used to combine measurements from the two sensors. Following a short calibration procedure, the electrogoniometer can be reliably used for measurement of flexion/extension angles of various hinge joints. The performance of the goniometer has been tested on a population of 21 healthy subjects performing flexion/extension of index finger, wrist and elbow. The proposed device achieves the quality of joint angle measurements comparable to that of commercial electrogoniometers, while having a significantly higher durability-to-cost ratio.